PostgreSQL"DESCRIBE TABLE"

Question

你如何DESCRIBE TABLE在PostgreSQL中使用相应的Oracle (使用psql命令)？

Answer 1

试试这个(在psql命令行工具中):

\d+ tablename

有关详细信息,请参阅手册.

Answer 2

除了PostgreSQL方式(\ d'thing'或\ dt'table'或\ ds'sequence'等等)

SQL标准的方式,如图所示在这里:

select column_name, data_type, character_maximum_length
from INFORMATION_SCHEMA.COLUMNS where table_name = '<name of table>';

它受到许多数据库引擎的支持.

Answer 3

如果要从查询而不是psql获取它,可以查询目录模式.这是一个执行该操作的复杂查询:

SELECT  
    f.attnum AS number,  
    f.attname AS name,  
    f.attnum,  
    f.attnotnull AS notnull,  
    pg_catalog.format_type(f.atttypid,f.atttypmod) AS type,  
    CASE  
        WHEN p.contype = 'p' THEN 't'  
        ELSE 'f'  
    END AS primarykey,  
    CASE  
        WHEN p.contype = 'u' THEN 't'  
        ELSE 'f'
    END AS uniquekey,
    CASE
        WHEN p.contype = 'f' THEN g.relname
    END AS foreignkey,
    CASE
        WHEN p.contype = 'f' THEN p.confkey
    END AS foreignkey_fieldnum,
    CASE
        WHEN p.contype = 'f' THEN g.relname
    END AS foreignkey,
    CASE
        WHEN p.contype = 'f' THEN p.conkey
    END AS foreignkey_connnum,
    CASE
        WHEN f.atthasdef = 't' THEN d.adsrc
    END AS default
FROM pg_attribute f  
    JOIN pg_class c ON c.oid = f.attrelid  
    JOIN pg_type t ON t.oid = f.atttypid  
    LEFT JOIN pg_attrdef d ON d.adrelid = c.oid AND d.adnum = f.attnum  
    LEFT JOIN pg_namespace n ON n.oid = c.relnamespace  
    LEFT JOIN pg_constraint p ON p.conrelid = c.oid AND f.attnum = ANY (p.conkey)  
    LEFT JOIN pg_class AS g ON p.confrelid = g.oid  
WHERE c.relkind = 'r'::char  
    AND n.nspname = '%s'  -- Replace with Schema name  
    AND c.relname = '%s'  -- Replace with table name  
    AND f.attnum > 0 ORDER BY number
;

它非常复杂,但它确实向您展示了PostgreSQL系统目录的强大功能和灵活性,并且可以帮助您实现pg_catalog掌握;-).请务必更改查询中的%s.第一个是Schema,第二个是表名.

Answer 4

您可以使用psql斜杠命令执行此操作:

 \d myTable describe table

它也适用于其他对象:

 \d myView describe view
 \d myIndex describe index
 \d mySequence describe sequence

资料来源:faqs.org

Answer 5

psql的当量DESCRIBE TABLE是\d table.

有关更多详细信息,请参阅PostgreSQL手册的psql部分.

Answer 6

您可以\d *search pattern * 使用星号来查找与您感兴趣的搜索模式匹配的表格.

Answer 7

除了\d+ <table_name>您已经找到的命令行之外,您还可以使用info_schema.columns使用信息模式来查找列数据.

SELECT *
FROM info_schema.columns
WHERE table_schema = 'your_schema'
AND table_name   = 'your_table'

Answer 8

这应该是解决方案：

SELECT * FROM information_schema.columns
WHERE table_schema = 'your_schema'
   AND table_name   = 'your_table'

Answer 9

你可以用这个:

SELECT attname 
FROM pg_attribute,pg_class 
WHERE attrelid=pg_class.oid 
AND relname='TableName' 
AND attstattarget <>0; 

Answer 10

使用以下SQL语句

SELECT DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE table_name = 'tbl_name' 
AND COLUMN_NAME = 'col_name'

如果替换tbl_name和col_name,它将显示您要查找的特定列的数据类型.

Answer 11

查询的这种变化(如在其他答案中所解释的)对我有用.

SELECT
 COLUMN_NAME
FROM
 information_schema.COLUMNS
WHERE
 TABLE_NAME = 'city';

这里详细介绍:http: //www.postgresqltutorial.com/postgresql-describe-table/

Answer 12

在postgres中，\d用于描述表结构。

例如\d schema_name.table_name

该命令将为您提供表的基本信息，例如列、类型和修饰符。

如果您想了解有关桌子使用的更多信息

\d+ schema_name.table_name

这将为您提供额外的信息，例如存储、统计目标和描述

Answer 13

当表名以大写字母开头时，您应该将表名放在引号中。

例子：\d "Users"

Answer 14

在MySQL中,DESCRIBE table_name

在PostgreSQL中,\ d table_name

或者,您可以使用此长命令:

SELECT
        a.attname AS Field,
        t.typname || '(' || a.atttypmod || ')' AS Type,
        CASE WHEN a.attnotnull = 't' THEN 'YES' ELSE 'NO' END AS Null,
        CASE WHEN r.contype = 'p' THEN 'PRI' ELSE '' END AS Key,
        (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid), '\'(.*)\'')
                FROM
                        pg_catalog.pg_attrdef d
                WHERE
                        d.adrelid = a.attrelid
                        AND d.adnum = a.attnum
                        AND a.atthasdef) AS Default,
        '' as Extras
FROM
        pg_class c 
        JOIN pg_attribute a ON a.attrelid = c.oid
        JOIN pg_type t ON a.atttypid = t.oid
        LEFT JOIN pg_catalog.pg_constraint r ON c.oid = r.conrelid 
                AND r.conname = a.attname
WHERE
        c.relname = 'tablename'
        AND a.attnum > 0

ORDER BY a.attnum

Answer 15

您还可以使用以下查询进行检查

Select * from schema_name.table_name limit 0;

示例：我的表有 2 列名称和密码。下面给出截图。

*使用PG admin3

Answer 16

描述表的最佳方式，例如列、类型、列修饰符等。

\d+ tablename or \d tablename

Answer 17

为了改进另一个答案的SQL查询（很棒！），这是一个经过修改的查询。它还包括约束名称，继承信息以及分解为组成部分的数据类型（类型，长度，精度，小数位数）。它还过滤掉已删除的列（数据库中仍然存在）。

SELECT
    n.nspname as schema,
    c.relname as table,
    f.attname as column,  
    f.attnum as column_id,  
    f.attnotnull as not_null,
    f.attislocal not_inherited,
    f.attinhcount inheritance_count,
    pg_catalog.format_type(f.atttypid,f.atttypmod) AS data_type_full,
    t.typname AS data_type_name,
    CASE  
        WHEN f.atttypmod >= 0 AND t.typname <> 'numeric'THEN (f.atttypmod - 4) --first 4 bytes are for storing actual length of data
    END AS data_type_length, 
    CASE  
        WHEN t.typname = 'numeric' THEN (((f.atttypmod - 4) >> 16) & 65535)
    END AS numeric_precision,   
    CASE  
        WHEN t.typname = 'numeric' THEN ((f.atttypmod - 4)& 65535 )
    END AS numeric_scale,       
    CASE  
        WHEN p.contype = 'p' THEN 't'  
        ELSE 'f'  
    END AS is_primary_key,  
    CASE
        WHEN p.contype = 'p' THEN p.conname
    END AS primary_key_name,
    CASE  
        WHEN p.contype = 'u' THEN 't'  
        ELSE 'f'
    END AS is_unique_key,
    CASE
        WHEN p.contype = 'u' THEN p.conname
    END AS unique_key_name,
    CASE
        WHEN p.contype = 'f' THEN 't'
        ELSE 'f'
    END AS is_foreign_key,
    CASE
        WHEN p.contype = 'f' THEN p.conname
    END AS foreignkey_name,
    CASE
        WHEN p.contype = 'f' THEN p.confkey
    END AS foreign_key_columnid,
    CASE
        WHEN p.contype = 'f' THEN g.relname
    END AS foreign_key_table,
    CASE
        WHEN p.contype = 'f' THEN p.conkey
    END AS foreign_key_local_column_id,
    CASE
        WHEN f.atthasdef = 't' THEN d.adsrc
    END AS default_value
FROM pg_attribute f  
    JOIN pg_class c ON c.oid = f.attrelid  
    JOIN pg_type t ON t.oid = f.atttypid  
    LEFT JOIN pg_attrdef d ON d.adrelid = c.oid AND d.adnum = f.attnum  
    LEFT JOIN pg_namespace n ON n.oid = c.relnamespace  
    LEFT JOIN pg_constraint p ON p.conrelid = c.oid AND f.attnum = ANY (p.conkey)  
    LEFT JOIN pg_class AS g ON p.confrelid = g.oid  
WHERE c.relkind = 'r'::char  
    AND f.attisdropped = false
    AND n.nspname = '%s'  -- Replace with Schema name  
    AND c.relname = '%s'  -- Replace with table name  
    AND f.attnum > 0 
ORDER BY f.attnum
;